Garments and other fabrics, including carpeting curtains, etc. become soiled with stains, fatty acids and other contaminants which attach to dust attracted to the garment during the normal course of wear.
Industrial uniforms become soiled with grease, oil, blood and other microbial contaminants. At present uniforms are cleaned by use of perchloroethylene (dry-cleaning) or by laundering. Laundering uses 1.2 gallons of water for each pound of clothing cleaned, requiring large energy inputs for heating, and resulting in large discharges of detergent and oil contaminated water. A typical industrial laundering operation washes a 400 lb. load. This would require 816 liters of water for washing and rinsing. Laundering operations typically utilize four rinses, the last rinse at temperatures of 200.degree. F. Assuming that the temperature of source water measures between 40.degree. F. (4.4.degree. C.) and 50.degree. F. (10.degree. C.) each wash cycle requires approximately 70,000 KCalories of heated water. Since this water is discarded, the energy is lost.
The discharges usually require installation of a water treatment facility on-site or they are made directly to a P.O.T.W. (Publicly owned treatment works). Most states require installation of on-site water treatment facilities.
Cleaning with perchloroethylene results in an exponential expansion of effluent in the form of oil contaminated perchloroethylene which must be handled and treated as hazardous waste.
The most frequently used solvent in the world for textile cleaning today is perchloroethylene. White mineral spirits and trichloroethylene, formerly of great significance, have, with the exception of China and Japan, have now virtually disappeared. In recent years two fluorocarbons, R113 and R11, entered the market for use as solvent cleaners; however, their use has been limited and is expected to end because of the Montreal Protocol, restricting and ultimately banning production of chlorofluorocarbons (CFC's), beginning in 1996.
The attendant deleterious safety and/or environmental effects of perchloroethylene makes it disadvantageous for use as a cleaning solvent. Organohalogens in general are environmentally suspect, but perchloroethylene use presents an additional set of concerns because of its high specific gravity of 1.626 (density 13.49 lbs/gal) and its high vapor pressure. Because the density of perchloroethylene is far greater than that of water (8.33 lbs/gal) and because it is clearly not biodegradable, perchloroethylene spillage presents a threat to groundwater with effects lasting many years. Moreover, in many instances in mixed use buildings, air emission guidelines are not met, even with new dry cleaning equipment. The recent problems documented in New York State show that the use of perchloroethylene is of ongoing concern.
White or mineral spirits, which are presently used in Japan and China, as well as other petroleum based solvents present a hazard and exhibit a proclivity to catch fire or even explode in dry cleaning equipment. This is a too-frequent occurrence in Japan where these solvents are in heavy use.
Typical prior art semi-aqueous washing processes employ two steps. The first step is a water-immiscible solvent wash step followed by a second step aqueous rinse. The second step is generally required because the solvents used in this process, unlike perchloroethylene or the CFC's, generally are not volatile and will not evaporate.
Degreaser compositions are presently used in various industrial settings to remove grease and oil from equipment, machinery and related metal-containing objects. Degreasers are used in the aircraft and automobile industry and the market is considered large worldwide. Presently, the primary degreaser solvent is perchloroethylene and other non-biodegradable chlorinated hydrocarbons are also used. The environmental hazard created by the use of these chlorinated degreasers complicates their use and has made them undesirable.